I was cruising down the highway yesterday and all of a sudden i heard a nasty noise coming from the engine, At 4.5k rpms and below a loud fast knocking/grinding noise is heard. Totally freaked me the F*** out! It can not be heard at higher rpms and the performance remained the same with no smoke coming out of the exhaust. thank god.... Anyone have a clue on what happened??? P.s. my bikes leaks oil time to time.. F4 with 25k

 

Could be your cam chain tensioner,

Hard to know exactly without hearing the noise.

 

Video fella with sound?

 

Never posted a vid can someone show me how? noob status